We will continue our investigations of changes in lens ultrastructure and biochemistry during aging and cataractogenesis. Human cataractous lenses will be classified using guidelines established by the Cooperative Cataract Research Group. Classified lenses will be evaluated by our four research units according to 1) lens protein chemistry, 2) morphology and physiology, 3) enzymology and 4) pharmacology of aldose reductase inhibitors. 1) Experimental work concerning the biochemical characterization of lens proteins consists of a) a new fractionation procedure of the soluble lens proteins by HPLC, b) further characterization of the F-11 protein, including an immunological study and c) further characterization of human hypermature cataractous lens proteins. 2) In our physiology laboratories, using diverse cytochemical and histochemical techniques and three dimensional reconstruction, the compartments of the human lens and their intercommunicating channels will be defined. Collaborative efforts with other Functional Units of the CCRG will involve a molecular analysis of intact lens fiber cells by use of specific antibodies for membrane and cytoplasmic components. Both immunofluorescent staining and labeling techniques for ultrastructural localization will be used. The communicating network of extracellular fluid through extracellular channels will be identified by the penetration pattern of Procion yellow. Studies with high voltage TEM of the cytoplasmic matrix will be extended. (3) To probe a possible cause of protein and ultrastructural changes, endopeptidase and exopeptidase activities in normal and cataractous human lenses will be quantified using synthetic fluorogenic and chromogenic substrates. (4) Since diabetic animal models and human testing for cataract reversal by aldose reductase inhibitors has begun, it is essential to have a sound basis on which to judge the success or failure of these compounds. Therefore, we will continue to study the fiber structure of treated and untreated diabetic human and experimental animal lenses using scanning electron microscopy. The ultimate goal of our multi-faceted research team is to diminish cataractogenesis and promote a reparative process.